Unidirectional ratchet wrench structure

Abstract

A unidirectional ratchet wrench structure has a wrench member, a pawl and a ratchet. The wrench member has an accepting space for accommodating the ratchet and an accepting space for accommodating the pawl. A toothed section of the pawl has a plurality of equiangular teeth and an irregular tooth. Since the irregular tooth is lower than the height of the equiangular teeth, the irregular teeth irregular tooth is capable of quickly disengaging from the equiangular teeth of the ratchet. The arc section and the toothed section have different arc measures and not push against the outer periphery of the ratchet at the same time, through the abutment of the pivoting point and the change of the center of gravity of the pawl when the wrench is rotated, the pawl is capable of producing a seesaw yaw movement to achieves the effect of quick engagement and disengagement.

What is claimed is: 
     
       1. A unidirectional ratchet wrench structure comprising:
 a wrench member having a head portion and a handle portion, the head portion comprising an accepting space connected to an accepting groove positioned toward the handle portion, the accepting groove having an arc shape; and 
 a pawl accepted in the accepting groove, the pawl having a concave upper surface facing the accepting space and comprising a toothed section and an arc section, the toothed section having a plurality of equiangular teeth and an irregular tooth adjacent to the arc section, an addendum angle of the irregular tooth being greater than an addendum angle of the equiangular teeth, and an addendum height of the irregular tooth being lower than an addendum height of the equiangular teeth and providing an escaping space; an arc measure of the arc section and an arc measure of the toothed section being unequal, and the arc section being lower than the toothed section, a lower surface of the pawl comprising a resting curve and an accommodating notch, the resting curve having at least one first portion and one second portion and a pivoting point between the first and second portions, the resting curve having a hook end facing toward the accommodating notch securing a first end of a spring in the accommodating notch, an upper surface of the accommodating notch comprising an upper arc and an extended surface, a limiting cavity formed between the extended surface and the upper arc and configured for positioning a second end of the spring, the second end of the spring configured to push against the accepting groove to provide an elastic force to the pawl via the first end of the spring, an end of the extended surface being shorter than an end of the arc section and the two ends being connected to form a beveled end; and 
 a ratchet having a plurality of equiangular teeth, a brake slot and an engaging slot at one end, a C-shaped fastener securing the ratchet in the accepting space, the equiangular teeth of the ratchet engaging with the toothed section of the pawl. 
 
     
     
       2. The unidirectional ratchet wrench structure as claimed in  claim 1 , wherein there is a 10-20° difference between an addendum angle of the irregular tooth and an addendum angle of the equiangular teeth. 
     
     
       3. The unidirectional ratchet wrench structure as claimed in  claim 1 , wherein an arc measure of the first and second portions of the resting curve are different, and the first portion is less than the second portion. 
     
     
       4. The unidirectional ratchet wrench structure as claimed in  claim 1 , wherein an unbiased length of the spring is equal to a length of the upper arc. 
     
     
       5. The unidirectional ratchet wrench structure as claimed in  claim 1 , wherein one side of the accommodating notch of the pawl has a stopping wall under the upper arc.